Testers Tinker with Tinker Bell-sized Fuel Tank

Metal coupons


If you really must know how we compared the fuel additives, here are the particulars.

• Fuel sample size: 250 milliliters.

• Sample composition: E-10 gasoline with 0.03-percent seawater added. This is not enough to cause phase separation, since E-10 can hold about 0.5 percent water in solution.

• Gasoline additive dose: All samples were treated at manufacturer recommended levels for seasonal storage. If the product was not recommended specifically for seasonal storage, the routine usage dose was doubled.

• Metal sample preparation: all samples were polished and weighed to within 0.1 mg.

• Air exposure: Each jar was fitted with a vent made from 8 inches of 3/16-inch clear vinyl tubing. EPA studies suggest that this will give an amount of breathing comparable to a fuel tank with a 5/8-inch vent that is 3 feet long.

• Temperature and humidity exposure: All samples were kept outside from April 20, 2012 to May 20, 2012 in the Chesapeake Bay area.

• Post-exposure coupon inspection: Each metal sample was visually observed and re-weighed. The change in weight and any evidence of tarnish were noted.

Although change in weight ranged from a 2-milligram gain to 20-milligram loss, we did not report these values, as in most cases, they were not statistically meaningful, the value depending very heavily on the size of the few largest pits. This methodology is common in coolant testing, where weight loss on pitted samples is extremely variable. The visual results were more consistent.

The test used three controls: one sample contained no seawater, no aftermarket gasoline additive, and was sealed with a tight lid to eliminate evaporation, oxygen absorption, and water absorption; one sample contained no seawater, no aftermarket gas additive, and was vented in the same manner as the test bottles; one sample contained 0.03 percent seawater and was vented in the same manner as the test bottles, but contained no aftermarket gasoline additive.

Practical Sailor has been independently testing and reporting on marine products for serious sailors for more than 45 years. Supported entirely by subscribers, Practical Sailor accepts no advertising or any form of compensation from manufacturers whose products we test. Testing is carried out by a team of experts from a wide range of fields including marine electronics, marine safety, marine surveying, sailboat rigging, sailmaking, engineering, ocean sailing, sailboat racing, and sailboat construction and design. This diversity of expertise allows us to carry out in-depth, objective evaluation of virtually every product available to serious sailors. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser with more than three decades of experience as a marine writer, photographer, boat captain, and product tester. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.


Please enter your comment!
Please enter your name here